java.lang.ClassCastException when using MLets

[newmand]

I am having problems using MLets. For example when I invoke the following code:

MLet mlet = new MLet(jarURL);
server.registerMBean(mlet, loader);
server.createMBean(clazz, obj, loader);

I get the below error:

19:25:17,596 ERROR [MBeanServerImpl] Unhandled exception instantiating class: com.wellsfargo.ice.management.ExportManager
java.lang.ClassCastException: org.jboss.mx.loading.UnifiedLoaderRepository2
at javax.management.loading.MLet.loadClass(MLet.java:276)
at java.lang.ClassLoader.loadClass(ClassLoader.java:250)
at org.jboss.mx.server.MBeanServerImpl.instantiate(MBeanServerImpl.java:790)
at org.jboss.mx.server.MBeanServerImpl.instantiate(MBeanServerImpl.java:266)
at org.jboss.mx.server.MBeanServerImpl.instantiate(MBeanServerImpl.java:243)
at org.jboss.mx.server.MBeanServerImpl.createMBean(MBeanServerImpl.java:286)
at com.wellsfargo.ice.management.Deployer.redeploy(Deployer.java:96)
at java.lang.reflect.Method.invoke(Native Method)
at org.jboss.mx.capability.ReflectedMBeanDispatcher.invoke(ReflectedMBeanDispatcher.java:284)
at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:517)
at org.jboss.jmx.adaptor.control.Server.invokeOpByName(Server.java:232)
at org.jboss.jmx.adaptor.control.Server.invokeOp(Server.java:200)
at org.jboss.jmx.adaptor.html.HtmlAdaptorServlet.invokeOp(HtmlAdaptorServlet.java:171)
at org.jboss.jmx.adaptor.html.HtmlAdaptorServlet.processRequest(HtmlAdaptorServlet.java:77)
at org.jboss.jmx.adaptor.html.HtmlAdaptorServlet.doPost(HtmlAdaptorServlet.java:59)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:366)
at org.mortbay.jetty.servlet.WebApplicationHandler.dispatch(WebApplicationHandler.java:284)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:577)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1674)
at org.mortbay.jetty.servlet.WebApplicationContext.handle(WebApplicationContext.java:544)
at org.mortbay.http.HttpContext.handle(HttpContext.java:1624)
at org.mortbay.http.HttpServer.service(HttpServer.java:875)
at org.jboss.jetty.Jetty.service(Jetty.java:541)
at org.mortbay.http.HttpConnection.service(HttpConnection.java:785)
at org.mortbay.http.HttpConnection.handleNext(HttpConnection.java:935)
at org.mortbay.http.HttpConnection.handle(HttpConnection.java:802)
at org.mortbay.http.SocketListener.handleConnection(SocketListener.java:200)
at org.mortbay.util.ThreadedServer.handle(ThreadedServer.java:294)
at org.mortbay.util.ThreadPool$JobRunner.run(ThreadPool.java:743)
at java.lang.Thread.run(Thread.java:479)

I have to use the following code to successfully hot deploy:

URLClassLoader urlcl = URLClassLoader.newInstance(jarURL, Thread.currentThread().getContextClassLoader());
Object mgdObj = urlcl.loadClass(clazz).newInstance();
server.registerMBean(mgdObj, obj);

Am I using MLets incorrectly, or is there a bug somewhere in the MLet implementation in JBoss 3.0.3?

Thanks,

David

[juha]

its a bug, should be fixed by now

[cridam44]

Is this bug fixed in JB3.06 ?

Because i have some errors that look like to the previous one :

when doing :

mlet=new MLet(mleturl,this.classloader);
mlet.addURL(url);

java.lang.ClassCastException
07:31:37,652 ERROR [STDERR] at org.jboss.mx.loading.UnifiedLoaderRepository3.addClassLoader(UnifiedLoaderRepository3.java:510)
07:31:37,653 ERROR [STDERR] at javax.management.loading.MLet.addURL(MLet.java:231)
07:31:37,654 ERROR [STDERR] at javax.management.loading.MLet.addURL(MLet.java:247)

[cridam44]

I m having a similar issue in JB3.06 :

When doing :

mlet=new MLet(mleturl);
mlet.addURL("http://host/dir/");

i obtain :

java.lang.ClassCastException
08:46:35,395 ERROR [STDERR] at org.jboss.mx.loading.UnifiedLoaderRepository3.addClassLoader(UnifiedLoaderRepository3.java:510)
08:46:35,396 ERROR [STDERR] at javax.management.loading.MLet.addURL(MLet.java:231)
08:46:35,397 ERROR [STDERR] at javax.management.loading.MLet.addURL(MLet.java:247)

Is it also a bug or something fixed in other jboss version ?

[juhalindfors]

this was only fixed for JBoss HEAD (4.0) and MX stand-alone builds

[cridam44]

Is there any simple way to fix/patch the JBoss MX version embedded into the JB3.06 ? If yes, could you shortly described us how to ?

I think about the standalone build that could be deployed instead of the "release version" ...

[cridam44]

I tried with the jbossmx 1.1.2 version of jbossmx.jar that i put in the server/lib and i got the same errors. Does it exist a jbossmx stable build somewehere that i can use within my stable JB3 version that could erase this blocking (for me) issue ?

[juhalindfors]

You could try replacing the JBossMX libs with the current 1.1.2 release -- this one should contain the MLet fixes.

If that doesn't work, you can always try to patch the source release of 3.0.6 yourself. AFAICT, it only involves two patches to the javax.management.MLet class, you can find the details here:

http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/jboss/jmx/src/main/javax/management/loading/MLet.java.diff?r1=1.10&r2=1.11

apply the above first, then add this:

http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/jboss/jmx/src/main/javax/management/loading/MLet.java.diff?r1=1.12&r2=1.13

You can use CVS to generate the diff and then 'patch' on the MLet.java (if you're on windows use cygwin for both 'cvs' and 'patch').

[cridam44]

Thanks juha, i merged the diffs into a MLet.java (i joined the code below).
Now the classcast has disappeared BUT some mistake remains to me :
I used the addURL to also add jar files in the MLet loader. I used this tip to overload the uncontrolled DefaultLoaderRepository behaviour of the JMX1.0/1.1 impl.

With the code you gave me, when using addURL we systematically passed by the UnifiedLoaderRepository thanks to the system variable :LOADER_REPOSITORY_CLASS_PROPERTY...

As you know, the need to scope ear or mlets is a real one(typically when a specific library version is really needed OR when you simply don't want to deal with flat multi-classloader consequences...).
How can this kind of tip work with JBossMX?

[juhalindfors]

This is kind of an old one but I missed it amongst other work...

although I'm not sure I understand your question, what would you need addURL() to do?